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ML4

Sensibly equivalent to:
AC/P CV1179 NR57
    
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Although sometimes listed as a triode output valve, the ML4 was the definitive descendent of the famous (or infamous) Type KL1 of 1926 and was primarily a professional and military type, little used in domestic radios. It was introduced in 1929 and an improved version appeared two years later. The original envelope shape would have been balloon.
It was quite widely used as an RF oscillator, as a single-valve phase splitter, and as a driver for larger valves.
The specimen shown is from the 1940s.
The classic envelope is 42 mm in diameter and, excluding the B5 base pins, is 93 mm tall.
References: Datasheet, 1040 & 1043. Type ML4 was first introduced in 1929.

 

Pin Connections
B5
1
2
3
4
5
a
g1
h
h
k

 

Absolute Maximum Operating Conditions
Triode
Vh
Ah
Va
Vg
mAa
ra
gm
Pout
4.0
1.0
200
-13.5
17
3,700
2.7
0.65W
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated January 31, 2013.
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